During our first trip in our 2014 Georgetown 329DS we hooked up the city water and the fresh water tank promptly filled up and overflowed. Our first inclination was a bad check valve in the water pump. We called the dealer and they agreed. The big surprise came when the dealer checked out the system and found that the water pump was OK.
It had them stumped for a while, but the problem was that the factory had put the ID stickers in the wrong order on the panel. The inlet marked "City Water" is actually the fresh water tank fill. The "Black Tank Flush" input is actually the city water hookup, and the "Fresh Water Tank" is actually the black water tank flush. The dealer has ordered the new sticker set.
Since that was the only problem we found with our new rig we're pretty happy.